Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Record number 430807
Title Starch-related Enzymes during Potato Tuber Dormancy and Sprouting
Author(s) Sergeeva, L.I.; Claassens, M.M.J.; Jamar, D.C.L.; Plas, L.H.W. van der; Vreugdenhil, D.
Source Russian Journal of Plant Physiology 59 (2012)4. - ISSN 1021-4437 - p. 556 - 564.
DOI http://dx.doi.org/10.1134/S1021443712040115
Department(s) Laboratory of Plant Physiology
EPS-3
Publication type Refereed Article in a scientific journal
Publication year 2012
Keyword(s) adp-glucose pyrophosphorylase - solanum-tuberosum - developmental-changes - hexose-phosphate - gene-expression - metabolism - sucrose - phosphorylase - biosynthesis - tuberization
Abstract Activities of enzymes presumably involved in starch biosynthesis (ADP-glucose pyrophosphorylase, AGPase) and/or breakdown (starch phosphorylase, STP; amylases) were determined during potato (Solanum tuberosum L.) tuber dormancy and sprouting. Overall activities of all these enzymes decreased during the first stage of tuber dormancy. No clear changes were detected at the time of dormancy breaking and sprouting. However, when AGPase activity was monitored by in situ staining during the entire dormancy period, a clear decrease during the dormant period and a large increase before visible sprouting could be observed. This increase was especially evident near the vascular tissue and at the apical bud, which showed a very intensive staining. In situ staining of STP activity in sprouting tubers showed that the tissue distribution of STP was the same as for AGPase. As a possible explanation, direct starch cycling is suggested: STP produces glucose-1-phosphate during starch breakdown, which can be directly used as a substrate by AGPase for starch synthesis. Gene expression studies with the AGPaseS promoter coupled to the firefly luciferase reporter gene also clearly showed a higher activity in sprouting tubers as compared to dormant tubers, with the highest expression levels observed around the apical buds. The presence of amylase activity at dormancy initiation and AGPase activity persistent at the sprouting stage suggest that starch was cycling throughout the entire dormancy period. According to the in situ studies, the AGPase activity increased well before visible sprout growth and could therefore be one of the first physiological determinants of dormancy breakage.
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